The mukbangs, it a giant burrito in 5 bites, rock–paper–scissors “run and eat” challenge may look like harmless fun on Instagram, but medically, it’s a messy combination of speed, adrenaline and food.

Internet clout-seekers have devised a new foolhardy food challenge in which bozos play the hand-flinging “rock, paper, scissors” game to determine who has to ingest an obscene amount of fast food, as ...